An apnea is a period of time during which breathing stops or is markedly reduced. In simplified medical terms, an apnea occurs when a person stops breathing for 10 seconds or more. Apneas usually occur during sleep. Sleep apnea is a disorder characterized by a reduction or cessation of breathing airflow during sleep. A reduction or cessation of airflow during sleep causes a resultant drop in blood oxygen level. This reduced blood oxygen level is detected by the brain, which sends out a signal to the body to wake up and take a breath. Consequently, when an apnea occurs, sleep is disrupted. Sometimes this means the person wakes up completely, but sometimes this can mean the person comes out of a deep level of sleep and into a more shallow level of sleep.
There are two basic types of sleep apnea: central sleep apnea and obstructive sleep apnea. Of the two types, obstructive sleep apnea is more common. Central sleep apnea occurs when the brain does not send the signal to the muscles to take a breath, and there is no muscular effort to take a breath. Obstructive sleep apnea occurs when the brain sends the signal to the muscles and the muscles make an effort to take a breath, but they are unsuccessful because the airway becomes obstructed and prevents the flow of air. In some instances, a patient may have both forms of sleep apnea, in which case the patient is considered to have “mixed apnea.”
Obstructive sleep apnea is estimated to affect about 4% of men and 2% of women. The prevalence of obstructive sleep apnea can be correlated to obesity within a population, as obesity exacerbates obstructive sleep apnea. Some studies suggest that among obese patients, upwards of 70% have obstructive sleep apnea. Obstructive sleep apnea can cause or exacerbate existing conditions of high blood pressure, stroke, extreme daytime sleepiness, ischemic heart disease, insomnia and mood disorders. In addition, patients with obstructive sleep apnea who receive sedation, analgesia or anesthesia for diagnostic or therapeutic procedures are at increased risk for perioperative complications.
During sleep in a person not having obstructive sleep apnea, air passes through the nasal passages, behind the palate, uvula, and tongue base, through the throat muscles, between the vocal cords and into the lungs. With obstructive sleep apnea, undesirable growth, configuration, swelling or motility of the nasal passages, palate, tongue, and pharyngeal tissues can all contribute to narrowing of the airway. In some cases, people with obstructive sleep apnea have an airway that is more narrow than normal, usually at the base of the tongue and palate. When lying flat, the palate is normally above the air passage. As shown in FIG. 9, in an apneic patient, when the pharyngeal muscles relax, the palate can fall backwards. Similarly, as shown in FIG. 9, relaxation of the genioglossus muscle during sleep allows the base of the tongue to fall backwards. These events can obstruct the airway. In many case the tissues of the airway are often sucked together by the negative pressure of air traveling into the lungs. This tissue action can exacerbate the degree of obstruction because the harder the chest tries to pull air in, the greater the negative pressure, and the more the tissues of the airway are sealed together.
The treatment of obstructive sleep apnea may be either surgical or nonsurgical. Surgical options for sleep apnea, however, may involve painful recoveries and extended time off from work to heal. Surgical options are also dependent on an individual's specific anatomy and severity of sleep apnea. Surgical options for treatment of obstructive sleep apnea include nasal airway surgery, palate implants, uvulopalatopharyngoplasty, tongue reduction, genioglossus advancement, hyoid suspension, maxillomandibular procedures, tracheostomy and bariatric surgery. Because these surgeries carry risk and offer no guarantee of improvement, most patients with obstructive sleep apnea go through a regimen of non-surgical treatments before considering surgery. Non-surgical treatments for obstructive sleep apnea include postural sleeping changes, dental appliances, medications (decongestants and steroid sprays) and use of CPAP (continuous positive airway pressure) devices.
CPAP is probably the best, non-surgical treatment for obstructive sleep apnea. A CPAP machine blows heated, humidified air through a short tube into a mask affixed to the patient's face. CPAP uses air pressure to hold airway tissues open during sleep. By delivering air through a nasal or face mask under pressure, as the patient breathes, the gentle pressure holds the nose, palate, and throat tissues open. The effectiveness of CPAP requires that the mask must be worn snugly to prevent the leakage of air. This is often difficult because of the discomfort engendered by masks. Critically, if the mask does not fit correctly, the efficacy of CPAP drops significantly. Also, when employing a CPAP machine, it is important to use the lowest possible pressure that will keep the airway open during sleep. However, different pressures may be needed for different positions or levels of sleep. These pressure levels, however, must be determined in a clinical setting or require an “auto-titrating” feature on the CPAP machine. Hence another disadvantage of CPAP is that it is not always easy to use. Studies show that only 60% of people with CPAP machines actually use them. When actual use time is measured, only 45% of those patients that actually use the machines use them more than 4 hours per night. Of those people who begin a CPAP regimen, 25 to 50 per cent will stop using CPAP despite the persistence of symptoms.
Due to the compliance issues attendant to CPAP treatment modalities, other methods of maintaining airway patency have been proposed. In this regard, use of a nasopharyngeal tube has been proposed to maintain airway patency. Though originally designed for placement by a physician, some prior art airway maintenance devices are intended for nightly use at home by the patient. For instance U.S. Pat. No. 6,328,753 discloses a folded tube intended for insertion into a patient's nostril and into the nasal passage way. Using a tube, however, to maintain, biologic passageway patency has certain disadvantages. First, the tube must be made of a sufficiently rigid material to enable insertion into the oropharynx. The fact that the tube is constructed of such material and that the tube has a large surface area increases the possibility of irritating contact with body tissues. Similarly, the large surface area of the tube can interfere with the natural secretory functions of surrounding tissues and sinuses of the nasal cavities. Accordingly, a need exists for an improved patient-usable, upper airway patency device that eliminates or minimizes the deficits of prior art devices.